1. Technical Field
The present invention relates to a tool trajectory display device that displays a trajectory of a representative point of a machine tool, such as a tool tip point.
2. Description of Related Art
Conventionally, an instruction trajectory of a representative point of a machine tool, such as a tip point, is displayed, being superimposed on a feedback trajectory obtained by actually moving the representative point of the machine tool, such as a tip point, according to the instruction, to visually observe an error in the feedback trajectory with respect to the instruction trajectory.
For example, Japanese Unexamined Patent Publication No. 2013-69231 discloses displaying a latest feedback trajectory superimposed on a prior feedback trajectory. In other words, Japanese Unexamined Patent Publication No. 2013-69231 discloses a technique of displaying on a display unit a plurality of superimposed pieces of trajectory data that have almost identical machining start positions and different machining conditions. Therefore, Japanese Unexamined Patent Publication No. 2013-69231 is advantageous in displaying a plurality of pieces of trajectory data with changed machining conditions, whereby the change in the trajectory data can be visually analyzed.
Machining of a particular workpiece, for example, blades of an impeller, requires repetitive machining of an identical shape. Specifically, after machining a blade of an impeller, the impeller is rotated around the rotational axis by a predetermined angle to machine another blade of the impeller in the same way, and this task is repeated.
The trajectory followed by such machining includes repetition portions with a plurality of rotated start positions. As such, the trajectory display device is required to display on the display unit a plurality of repetition portions with identical machining conditions and different machining start positions. Further, the same is true when machining is performed in accordance with a trajectory that has repetition portions with a plurality of translated start positions.
Although Japanese Unexamined Patent Publication No. 2013-69231 can display a plurality of superimposed pieces of trajectory data with almost identical machining start positions and different machining conditions on the same coordinate system, it is difficult for Japanese Unexamined Patent Publication No. 2013-69231 to display a plurality of superimposed pieces of trajectory data with the identical machining conditions and different machining start positions on the same coordinate system. As such, when machining a workpiece that requires repetition of similar machining, the trajectory display device disclosed in Japanese Unexamined Patent Publication No. 2013-69231 can neither compare nor evaluate in the same coordinates with high precision whether the shapes of the repetition portions are identical.
The present invention has been made in consideration of the above problem, and has an objective of providing a tool trajectory display device that can easily compare the shapes of the repetition portions of the trajectories when a machining program includes a plurality of repetition portions for repeatedly processing identical or symmetric shapes.